One field of plant growth regulation which has become particularly economically important is the field of harvest aid compounds. The field of harvest aid utilization includes a wide variety of primary effects, including the defoliation of the crop plant; the desiccation of its leaves, stems, and other aerial organs; the control of late-season regrowth (e.g., for cotton); the promotion or inhibition of fruit or flower abscission: the concentration of crop maturity: and the enhancement of consumer-preferred quality factors.
Under normal conditions, many crop plants do not mature uniformly or in a timely fashion that would facilitate an efficient and optimum harvest, either due to equipment scheduling or weather considerations. Crops such as cotton, potato, sunflower, and seed legumes require either desiccation or defoliation before harvest can be effectively accomplished. Thus, for example, when cotton is not defoliated the leaves can interfere with mechanized picking apparati which are frequently employed. Also, leaves can contaminate the cotton lint with trash or green stain, which reduces the quality of the fiber or reduces the efficiency of the ginning process. Likewise, potato vines need to be desiccated for efficient mechanical digging. In addition, upon desiccation of potato leaves and stems, the tuber skin matures and becomes less susceptible to damage from the digger and postharvest handling. Seed legumes and sunflowers are also mechanically harvested, and this process is facilitated if the leaves and stems are removed or desiccated. As with cotton and potato, such defoliation or desiccation also ripens the seed uniformly, accelerates the rate of seed maturation, and conditions the pod or head for easy harvest. In addition, the mechanical harvest of many fruit species, such as citrus, grape and olive, is routinely facilitated by the application of chemical abscission inducing agents.
Moreover, a major problem in many areas is the uncontrolled growth of aquatic weeds such as water hyacinth, water lettuce, duckweed and the like. Because such weeds are often located in ecologically fragile areas, it is not desirable to treat such plants with the large dosages of herbicides necessary to effectively control such plants in their aqueous environs. Rather, resort to natural control, --i.e., insects which feed off such plants--has been the desired method of treatment. Unfortunately, the growth rates of many of these species is so rapid that such natural means of control is ineffective to adequately prevent such weeds from clogging waterways. Accordingly, it would be desirable to possess a means of retarding the growth of these aquatic weeds without employing extensive amounts of chemicals such that such insects could consume said plants at rates equal to or in excess of such rate of growth, thereby effectively controlling said plants.
European Patent Application No. 195,346 discloses a class of 3-carbonylphenyl uracil derivatives which are described as being effective herbicides. Consequently, it is completely unexpected that such compounds, when applied appropriately, will act as harvest aids for several important crops. Moreover, it is surprising that such compounds, when applied in desirably low concentrations, will retard the growth of aquatic weeds such that said weeds may be then controlled by natural means.
Accordingly, it is an object of this invention to provide a method for regulating the growth of crops such that they may be more efficiently and economically harvested.
It is a further object of this invention to provide a method for retarding the growth of aquatic weeds such that said weeds may be effectively controlled by natural means.